There is a substantial body of work focused on various types of coatings for metal substrates. Coatings can provide decorative and/or functional properties to the substrate. Decorative coatings are used to provide a surface with a specific appearance such as color or gloss. Functional coatings provide the substrate with other properties, e.g., abrasion resistance and corrosion resistance.
Consider the case of architectural hardware. Brass is the material that is most highly prized by the marketplace today in the United States for use on door handles, knobs, escutcheons etc. Brass, unfortunately, is prone to oxidation, tarnishing and corrosion when exposed to atmospheric conditions. These chemical processes severely affect the appearance of the brass, making it less visually appealing. Due to these tendencies for the brass to undergo corrosion, it must be protected in order to avoid the degradation of its appearance. Therefore, corrosion-resistant coatings are desired.